Blender crashes on baking (ambient occlusion)
Well, Although I've only Baked once, I notice you have the width and height of your texture map set at 4096, I would suggest maybe lowering that to 2048. According to Darrin lile's videos on Texturing, he encountered glitches when using a number that high. 

Now if this is the same as your other textures you should probably scale them down too, just for the sake of them matching up. I could be totally wrong, but I'm just telling you what I think may work. I hope I'm helping here!